Geotechnical behaviour of guar gum-treated soil

Soil stabilization through biological methods is a sustainable, efficient and long-term alternative to conventional techniques. An elaborate study on the engineering behaviour of guar gum-treated soil, a gum-based biopolymer, is carried out through a concise experimental programme. The dry density of the treated soil shows a marginal increase and its optimum moisture content decreases with the increase in guar gum content. The marginal change in dry density over a range of water contents indicates that guar gum-treated soil can be compacted at low energies and that its sensitivity to changes in water content is not appreciable. The stress-strain behaviour of the treated soil indicates that guar gum stiffens the soil matrix, enabling it to resist loads at lower strains. The gain in strength of the soil-guar matrix is seen to depend on both the biopolymer content and the curing time. There is a substantial increase in the unconfined compressive strength of the treated soil - nearly 45% immediately and 131% after 90 days of curing at a 2% guar gum content. The compressibility of the soil is effectively reduced as the addition of guar gum results in the formation of hydrogels that not only clog the pore spaces, but also stiffen the soil matrix. Guar gum is susceptible to degradation; and hence, durability tests are conducted. The results show that there is no appreciable degradation of the treated soil samples within the investigated period of 90 days. (C) 2019 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.